The variety of temporal and structural constraints on the Alpine tectonometamorphic signature of the metamorphic core of the Betic-Rif orogen (Alboran Domain) has supported a long-lasting debate regarding the Alpine tectonic and geodynamic evolution of the Western Mediterranean region. Uncertainty still exists on the timing and tectonic significance of (a) the Alpine orogenic construction; (b) exhumation of the deep roots of the orogen; and (c) transition from orogenic shortening to crustal extension. In this study, we address these major geological issues by focusing on the lower-grade units of the Alboran Domain (Upper Sebtides and Ghomarides) exposed in the Rif belt of northern Morocco. Through a multidisciplinary approach that integrates mesostructural and microstructural investigations with X-ray diffraction, quantitative mineral chemistry, and ⁴⁰Ar/³⁹Ar geochronology, a 20 Ma long tectonic history is reconstructed, which involves burial of the tectonic units at depth (late Eocene) and postorogenic exhumation under brittle conditions in the upper crust (early Miocene). We document a Priabonian (∼37-34 Ma) D₁/M₁ progressive compressional deformation, during the formation of a SW-verging orogenic wedge (present coordinates), accreted toward the Africa plate. Brittle extensional detachment tectonics operated during the Burdigalian (∼18-17 Ma), controlling the thinning of the previously structured Alboran Domain nappe stack and the final exhumation of the Alpine orogenic units. We propose that transition from orogenic build-up to collapse in the hinterland of the Betic-Rif orogen occurred when the retreat of the Apennine-Maghrebian subduction was efficient to drive transition from shortening to extension in the back-arc domain of the western termination of the Apennine-Maghrebian subduction zone.

中文翻译：

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摩洛哥内里夫链 Alboran 域高山造山运动和后造山运动的时间

对 Betic-Rif 造山带（阿尔博兰域）变质核心的高山构造变质特征的各种时间和结构限制支持了关于西地中海地区高山构造和地球动力学演化的长期争论。(a) 高山造山构造的时间和构造意义仍存在不确定性；(b) 造山带深层根部的挖掘；(c) 从造山带缩短到地壳伸展的转变。在这项研究中，我们通过关注摩洛哥北部 Rif 带中暴露的 Alboran 域（上 Sebtides 和 Ghomarides）的低品位单元来解决这些主要地质问题。通过将细观结构和微观结构研究与 X 射线衍射、定量矿物化学相结合的多学科方法，⁴⁰ Ar/ ³⁹ Ar 地质年代学，重建了 20 Ma 长的构造历史，包括深部构造单元的掩埋（始新世晚期）和上地壳（早中新世早期）脆性条件下的造山后剥露。我们记录了一个 Priabonian (∼37-34 Ma) D ₁ /M ₁在形成接近西南的造山楔（当前坐标）期间，逐渐压缩变形向非洲板块增加。在 Burdigalian (∼18-17 Ma) 期间，脆性伸展分离构造起作用，控制先前构造的 Alboran Domain 推覆叠层的变薄和高山造山单元的最终折返。我们认为，当亚平宁-马格里布俯冲的撤退有效地推动了西端弧后区域从缩短向延伸的转变时，Betic-Rif 造山带腹地的造山形成向塌陷转变。亚平宁-马格里布俯冲带。